Go with Atom
I’m not sure anyone cares about my opinion in this particular discussion, but I agree 100% with James Robertson’s view (who references this post by DeWitt Clinton): If you need to provide content syndication features in any form, you should definitely go with Atom (which is an IETF standard), not RSS (which is, technically speaking, crap). Convert as needed.
In case you wonder why RSS hasn’t been “fixed”, James provides the answer:
RSS could have been the unitary spec had Dave not been a complete jerk, and people like Scoble bear some responsibility for that by never, ever calling him on his BS.